schnuersi said...

Because the gun is unnecessarily large. It also would need a very large opening to shoot trough.

Given that a number of turret systems feature externally mounted coaxial guns that isn't necessarily so much of a problem.

schnuersi said...

You definetly would [get more dispersion with six barrels]. Which means you waste a lot of ammo.

Only if the increased dispersion is significant. Plus you would be comparing a hot single barrel with a much cooler six-barrel arrangement. Plus a modern FCS means you waste less ammo than an older FCS machine gun.

schnuersi said...

Is that the case? [that reduced fire rates on miniguns are available due to user requests]
Which guns would that be? Who requested that, for which prupose?

Profense's miniguns:

 https://rumble.com/vsrzeh-mini-gun-demo-by-profense-at-shot-show-industry-day-at-the-range.html

Requested by users who have them mounted on ground vehicles, for the purpose of reducing ammunition usage when it's not needed. I infer that's special forces.

schnuersi said...

and why would this be necessary?

Its a fact that not a single military so far has ever seen the need to use a gun as coax that is significantly more capable than a common GPMG or MMG. At best a heavy barrel version is used or simply two guns are mounted. Even water cooled coax or AFV guns have been very rare and usually been dispensed with quickly even at the time when water cooled MMGs have been common.
No one used multi barrel guns in this role.
So cooling of coax MG doesn't seem to be that much of an issue. As well as burst length.

There simply is no tactical need for it. Just because something can be done doesn't mean it needs to be done or should be done.

Conversely, just because no-one has done it so far doesn't mean that it shouldn't be done. No one fitted a camera system to an AFV until they did, as the performance of cameras and data transmission coupled with powered gun control improved. Now most AFVs carry more cameras than Hubble.

In terms of mounted machine guns, I recall that the Germans in WW2 favoured the MG34 over the MG42 because barrel change under armour was easier. The British Army operate a coaxial gun with a quick change (and heavy) barrel in the L94A1 chain gun. Water cooled AFV guns were typically dispensed with because the water jacket was vulnerable. See the comedy barrel shrouds on the Australian Sentinel prototype.

I've read that suppression effect is greater the more different characteristics are in play, so HE + MG fire has greater effect than either alone. Sticking in vastly different rates of fire might add to this.

schnuersi said...

Miniguns are very rarely used in ground vehicles especially AFVs. If they are its usually because they have a very high rate of fire.
This is what I am refering to. The use of a minigun in a helicopter or any flying vehicle in general is not what I am talking about.

I apologise. I knew that but my username was not chosen randomly.

It's only relatively recently that motor technology has permitted easy changes to fire rate without impacting reliability.

RovingPedant said:

Given that a number of turret systems feature externally mounted coaxial guns that isn't necessarily so much of a problem.

In this case the gun would not be protected by armor. Which for a fairly large and complex weapon doesn't seem like a good idea.

RovingPedant said:

Only if the increased dispersion is significant.

It is significant. I know the disperson of a M134D. Have seen it first hand. Its plain awefull. Conventional machine guns like the MG3 or MG4 have orders of magnitude less dispersion.

RovingPedant said:

Requested by users who have them mounted on ground vehicles, for the purpose of reducing ammunition usage when it's not needed. I infer that's special forces.

Ok so there is one case. This doesn't allow for the conclusion that this is allways a good solution for a general purpose gun. It could and most likely is a request that has been triggred by a specific situation and personal preference.

RovingPedant said:

Now most AFVs carry more cameras than Hubble.

Which is not true to start with. Some AFVs do. In most cases they carry one or two cameras. If it is a good idea to mount lots of cameras onto AFVs is still undecided. The reasons are also completly unrelated to the problem we are discussing so no conclusions can be drawn.

RovingPedant said:

I recall that the Germans in WW2 favoured the MG34 over the MG42 because barrel change under armour was easier.

No that is not correct. The barrel change of the MG42 is far easier and quicker. The coax MGs of German tanks of WW2 had to be fed from the right because the loaders position at this time has been on the right side of the turret. The MG34 can easily be mounted upside down for right side feeding. This is not possible to the same degree with the MG42.
Nowadays the loader is on the left and the MG3 mounted on the left side of the main gun. Even though the barrel changing port is on the right side facing the main gun its easiy and quick to change barrels.

RovingPedant said:

The British Army operate a coaxial gun with a quick change (and heavy) barrel in the L94A1 chain gun.

So apparently quick change and heavy barrel is sufficient.

RovingPedant said:

Sticking in vastly different rates of fire might add to this.

Pure speculation.
The experience of the German army suggests otherwise for example. Since there are few reliable examinations of supression its impossible to draw any conclusions.

schnuersi said...

Which is not true to start with. Some AFVs do. In most cases they carry one or two cameras. If it is a good idea to mount lots of cameras onto AFVs is still undecided. The reasons are also completly unrelated to the problem we are discussing so no conclusions can be drawn.

Most concept/new AFVs usually mount quite a few, while Hubble doesn't really mount that many. The point there is that while using lots of cameras may or may not be a good idea, it is the development of the technology that has made it more of a question than the previous situation where they clearly didn't have enough resolution/capability to be worth while. Things change and you have to revisit concepts with an open mind once in a while to find out if the reason is still valid

schnuersi said...

No that [MG34 barrel change in easier under armour] is not correct. The barrel change of the MG42 is far easier and quicker. The coax MGs of German tanks of WW2 had to be fed from the right because the loaders position at this time has been on the right side of the turret. The MG34 can easily be mounted upside down for right side feeding. This is not possible to the same degree with the MG42.

Isn't the barrel change procedure for the MG34 to pivot the receiver about a pivot parallel to bore axis and withdraw the barrel directly backwards, while the MG42 requires space alongside the barrel shroud since the barrel comes out sideways, pivoting somewhere about the muzzle device? Surely this means that the MG34 could be mounted further through an armour plate, particularly for bow gunner positions. My thinking here is that it is necessary to change the barrel on a single barrel gun.

schnuersi said...

So apparently quick change and heavy barrel is sufficient.

The key bit being the quick change, which adds certain complications onto the design and where you can mount the gun. If it's external or on a RWS then changing the barrel is not so easy. If you need to change the barrel, then overheating is an issue that needs to be addressed in one way or another. That RLS even prototyped the 3-barrel auto-change thing suggests that weapon overheating is a concern. Even if it can be managed, making the management easier is probably worth a look at.

schnuersi said...

Ok so there is one case. This doesn't allow for the conclusion that this is allways a good solution for a general purpose gun. It could and most likely is a request that has been triggred by a specific situation and personal preference.

One case that shows that one of the main objections for the use of miniguns no longer exists.

schnuersi said...

In this case the gun would not be protected by armor. Which for a fairly large and complex weapon doesn't seem like a good idea.

Few if any RWS feature protection for the gun, but if you wanted to protect the gun the firing barrel is only every in one place and you could protect all by the firing barrel if you could deal with the cooling and gas that would trap. Which you have to do with most GPMGs anyway. Accepting that a minigun on high rate will be generating quite a bit more gas, but at the same time there's a longer lock time so less gas is in the case when it's ejected.

I don't think that a minigun is definitely the best solution to an unknown problem, but that it offers certain benefits that make it worth investigating at least. In the end it might cost too much or the dispersion might be unacceptable. If we're considering auto-change barrels on an MG3 or various exotic calibres, why not?

CV90 with non penetrating RWS could hold 2+11 or 3+10

Refleks said:

CV90 with non penetrating RWS could hold 2+11 or 3+10

Sadly not. The Armadillo seats 3+8 https://www.military-today.com/apc/cv90_armadillo.htm

No idea whether that is whith shock resistant seats or not.

graylion said:

The Armadillo seats 3+8

Looks like it's 3 + 7.  Armadillo CV90 light tracked armoured vehicle personnel carrier BAE Systems.flv - YouTube

graylion said:

No idea whether that is whith shock resistant seats or not.

Fairly good view of the seats here:  https://youtu.be/sP79YZvaRdQ?t=140

No, there is definitely enough room for my assertion, you can see a scale cutaway and seating arrangement / turret basket here.

https://tanks-encyclopedia.com/cv9040a-and-b/

The interior dimensions are larger than that of an M-113. The armadillo's seating arrangement obviously places the commander and gunner into the hull taking up just as much swept floor area as the turret basket did (you can even see the circular outline of where the turret would have been in the digital cutaway) or even more since you're losing a seat. 

This is probably more ergonomic for them but its self evidently not the most efficient use of space if you wanted to maximize dismounts, which they have no incentive to offer because 10-11 man squads are unusual rather than the norm. 

Refleks said:

No, there is definitely enough room for my assertion...

The armadillo's seating arrangement obviously places the commander and gunner into the hull taking up just as much swept floor area as the turret basket did (you can even see the circular outline of where the turret would have been in the digital cutaway)...

In the second video I linked, the commander and gunner seats appear to be further forward than shown in the digital cutaway, placing the commander right up against the front wall, but still with insufficient space to add another passenger seat behind him.

It looks to me like your assertion is iffy at best.  Your conclusion is based on a simplified line drawing that does not show every detail.  The video of the actual vehicle interior makes it appear somewhat doubtful that it is practical to install another passenger seat.

RovingPedant said:

Most concept/new AFVs usually mount quite a few,

Concept and prototype do.
There are few in service.
The question also is why are they sticking cameras on everything in large numbers? Not because it is usefull or improves anything. Its cheap. It also appears high tech and fancy.

RovingPedant said:

Things change and you have to revisit concepts with an open mind once in a while to find out if the reason is still valid

True but its also not an end to itself. The miniguns is a bad concept to start with. Has been back in the day when it was developed and still is. Now arguing to not use what the gun has been intended for and doesn't do very well to do something it has not been developed for and as a result does only very bad is not revisiting. Its trying to shohorn a bad solution into another problem in an attempt to... to do what really?
If the manufacturer had suggested it I would get it. They want to sell more stuff. Sobody with no affiliation?

RovingPedant said:

Isn't the barrel change procedure for the MG34 to pivot the receiver about a pivot parallel to bore axis and withdraw the barrel directly backwards, while the MG42 requires space alongside the barrel shroud since the barrel comes out sideways, pivoting somewhere about the muzzle device?

Yes.

RovingPedant said:

Surely this means that the MG34 could be mounted further through an armour plate,

The barrel shroud of the MG42 has a bigger diameter compared to the MG34. Without redesign they will not fit trough the same opening anyways.
 

The space you need to change the barrel of an MG34 or MG42 is more or less the same. But in different places. As you say the MG34 if mounted pivots the receiver out of the way and the barrel goes straight back. But the receiver needs to pivot somewhere. This includes the firing group, pristol grip, belt feed and gets a fiddly if there still is a belt connected to the feeding.
The MG42 has the side port. There is not really a pivot point. The barrel is moved to the side so the locking block clears the gun and is then pulled allmost straight back in paralel to the gun. So basically on the right side you need enough space for the barrel to get out of the gun and a little more for a hand to grab it. That is a far more efficient arangement than that of the MG34. Generally speaking and especially if used from bipod.

RovingPedant said:

particularly for bow gunner positions.

irrelevant since I am argung for coax use and allmost no modern vehicle has such a mount or anything similar.
In the case of the MG42 the ball mounts would have had to be redesigned too. The continued use of MG34 in AFV especially tanks is because they did not want to redesign, the gun offered specific advantages the way it was used and it worked good enough.
BTW the coax version of the MG34 had a special modified barrel sleeve. It was not the same as the GPMG version.

RovingPedant said:

One case that shows that one of the main objections for the use of miniguns no longer exists.

One case that shows a specific group of people (or even only one persone) does so.
BTW what would be the main objection? The main objections are that a minigun is an inefficient design and as a result to large and heavy, its inaccurate and needs electrical power. None of these would be adressed by changing the ROF. As mentioned quite the oposit. Since the only pro a minigun has is the ROF the only reason to use such a gun at all would disappear.

RovingPedant said:

If you need to change the barrel, then overheating is an issue that needs to be addressed in one way or another.

Yes. But there are far better, more efficient ways to do so instead of using a minigun.

RovingPedant said:

That RLS even prototyped the 3-barrel auto-change thing suggests that weapon overheating is a concern.

No necessarily. It only shows that they predicted that it could be a concern and wanted a product to offer should this happen.
The thing is the RWS GPMGs overheating had been a problem caused by the specific conditions. Mostly the absense of more powerfull guns and fire support options. Once .50, 40 mm AGL and 20 mm ACs had been fielded as well as 155 mm indirect fire support made available the need to use GPMGs as main and only asset dissapeared. The time length of typical engagements went down significantly as well. All of a sudden overheating ceased to be an issue. More or less the same as it happened with the G36.
The problem was not overheating guns and it could not have been solved by making the guns withstand more heat. The issue had been desisions made at higher levels and the lack of appropiate weapons. MGs that would have endured longer would not have solved anything.

RovingPedant said:

Few if any RWS feature protection for the gun,

That is not coax use.
But I would still argue that a low ROF minigun is a bad choice.
 

RovingPedant said:

If we're considering auto-change barrels on an MG3 or various exotic calibres, why not?

So the argument is: if only bad and outright stupid suggestions are on the table, why not thing about a low ROF minigun as well?
Not the way I think about solutions but now I get it. Good and effective solutions are out and only the rest is to be concidered. In this case a low ROF minigun fits very well.

Refleks said:

No, there is definitely enough room for my assertion, you can see a scale cutaway and seating arrangement / turret basket here.

You have to be terribly carefull in the case of the CV90.
There different version differ quite a bit. The original Swedish version with 8 seats for dismounts do not have modern blast protection. As a matter of fact few CV90 do have these. This simply has not been a thing when the CV90 had been developed. If they are uprgaded and equiped to higher standarts the number of seats goes down. The improved Swedish versions loose one seat. The Mk IV is a substancial improvement but still not on the same level as more modern vehicles. There is a limit to what can be achieved with a given size and weight.
This is why they came up with the Armadillo version of the APC version. As a COIN/LIC vehicle with full scale modern protection at the expense of firepower. This is why the Armadillo "only" seats 7+2.
What a lot of people forget is that blast protection doesn't only mean portected seating a spall liners. It also means each and every bit of gear has to be stowed in a way it can not be ripped loose and becomes a danger. This means you need space for the equipment and personel gear as well. This eats up a lot of volume. Its visible on the Armadillo drawing for example. The "gaps" are not empty in reality. This is storage space.

The question is kind of vehicle does Elbonia need. If COIN and LIC is off the table this increases the number of options. As does if they don't care for their soldiers to the same degree as other nations do.

There also is the question if its a good idea to cram many soldiers into one vehicle. 10 allready is an awefull lot.